Tutorial by Examples: en

int* foo(int bar) { int baz = 6; baz += bar; return &baz; /* (&baz) copied to new memory location outside of foo. */ } /* (1) The lifetime of baz and bar end here as they have automatic storage * duration (local variables), thus the returned pointer is not valid! */ ...

Use len() to get the one-dimensional length of a list. len(['one', 'two']) # returns 2 len(['one', [2, 3], 'four']) # returns 3, not 4 len() also works on strings, dictionaries, and other data structures similar to lists. Note that len() is a built-in function, not a method of a list objec...

Let's say you want to generate counts or subtotals for a given value in a column. Given this table, "Westerosians": NameGreatHouseAllegienceAryaStarkCerceiLannisterMyrcellaLannisterYaraGreyjoyCatelynStarkSansaStark Without GROUP BY, COUNT will simply return a total number of rows: SELE...

Due to auto unboxing, one can use a Boolean in an if statement: Boolean a = Boolean.TRUE; if (a) { // a gets converted to boolean System.out.println("It works!"); } That works for while, do while and the condition in the for statements as well. Note that, if the Boolean is null...

$( "#accordion" ).accordion( "enable" ); This method will enable an accordion. This will enable a disabled accordion or simply do nothing on an already enabled accordion. This method does not take any arguments.

A typical email has three main components: A recipient (represented as an email address) A subject A message body Sending mail in PHP can be as simple as calling the built-in function mail(). mail() takes up to five parameters but the first three are all that is required to send an email (al...

Switch statements compare the value of an expression against 1 or more values and executes different sections of code based on that comparison. var value = 1; switch (value) { case 1: console.log('I will always run'); break; case 2: console.log('I will never run'); break;...

A lookbehind can be used at the end of a pattern to ensure it ends or not in a certain way. ([a-z ]+|[A-Z ]+)(?<! ) matches sequences of only lowercase or only uppercase words while excluding trailing whitespace.

Ruby offers the expected if and else expressions for branching logic, terminated by the end keyword: # Simulate flipping a coin result = [:heads, :tails].sample if result == :heads puts 'The coin-toss came up "heads"' else puts 'The coin-toss came up "tails"' end ...

If you want to use a pipe character (|) in the content of a cell you'll need to escape it with a backslash. Column | Column ------ | ------ \| Cell \|| \| Cell \| This results in the following table: ColumnColumn| Cell || Cell |

currentColor returns the computed color value of the current element. Use in same element Here currentColor evaluates to red since the color property is set to red: div { color: red; border: 5px solid currentColor; box-shadow: 0 0 5px currentColor; } In this case, specifyin...

You can indent the text inside here documents with tabs, you need to use the <<- redirection operator instead of <<: $ cat <<- EOF This is some content indented with tabs `\t`. You cannot indent with spaces you __have__ to use tabs. Bash will remove empty space befo...

Listed from least expensive to most expensive at run-time: str::strtok is the cheapest standard provided tokenization method, it also allows the delimiter to be modified between tokens, but it incurs 3 difficulties with modern C++: std::strtok cannot be used on multiple strings at the same t...

Since Groups are "numbered" some engines also support matching what a group has previously matched again. Assuming you wanted to match something where two equals strings of length three are divided by a $ you'd use: (.{3})\$\1 This would match any of the following strings: "abc$...

Deleting the last element: std::vector<int> v{ 1, 2, 3 }; v.pop_back(); // v becomes {1, 2} Deleting all elements: std::vector<int> v{ 1, 2, 3 }; v.clear(); // v becomes an empty vector Deleting element by index: std::vect...

In standard pattern matching, the identifier used will shadow any identifier in the enclosing scope. Sometimes it is necessary to match on the enclosing scope's variable. The following example function takes a character and a list of tuples and returns a new list of tuples. If the character existed...

This demonstrates a filter on a for-loop, and the use of yield to create a 'sequence comprehension': for ( x <- 1 to 10 if x % 2 == 0) yield x The output for this is: scala.collection.immutable.IndexedSeq[Int] = Vector(2, 4, 6, 8, 10) A for comprehension is useful when you need to crea...

A CLOS class is described by: a name a list of superclasses a list of slots further options like documentation Each slot has: a name an initialization form (optional) an initialization argument (optional) a type (optional) a documentation string (optional) accessor, reader and/or wr...

In Go, you can declare multiple variables at the same time. // You can declare multiple variables of the same type in one line var a, b, c string var d, e string = "Hello", "world!" // You can also use short declaration to assign multiple variables x, y, z := 1, 2, 3 ...

/* declare items of the enum */ #define FOREACH \ X(item1) \ X(item2) \ X(item3) \ /* end of list */ /* define the enum values */ #define X(id) MyEnum_ ## id, enum MyEnum { FOREACH }; #undef X /* convert an enum value to its identifier */ const char * enum2string(int...